Alarm device

ABSTRACT

An alarm device which is actuated by intrusion into the protected area to cause an intermittent signal to be produced indicating the intrusion. An electronic circuit is employed to selectively cause actuation of the alarm device.

United States Patent Inventor George Puig l4] Salven SL, Rio Piedras Heights, Rio

Piedras, P.R. Appl. No. 733.360 I Filed May 31, I968 Patented July 20, 1971 ALARM DEVICE 10 Claims, 1 Drawing Fig. U. S. Cl 340/63 R, 340/276 R, 307/10 AT Int. Cl ..G08bl3/00, B60r 25/00 Field of Search ..340/52, 63,

References Cited UNITED STATES PATENTS 3,209,326 9/1965 Heiser Primary Examiner-John w. Caldwell Assistant Examiner-R. J. Mooney Analyzer-Birch, Swindler, McKie and Beckett ABSTRACT: An alarm device which is actuated by intrusion into the protected area to cause an intermittent signal to be produced indicating the intrusion. An electronic circuit is employed to selectively cause actuation of the alarm device.

PATENTEDJULZOISYI 3594.723

INVENTOR GEORGE Pugs ATTORNEYS A with a carand may be ALARM DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an alarm device and has particular utility for use in conjunction with automobilespThus the alarm u may be actuated by the opening of a car door, hood or trunk I l PNP llfillSlSlOFT-l 1s |llustrated,.hav|ng its emitter connected BRlEErDiESCRlPTlON OF THE DRAWING Y The drawing shows a schematic'diagram of the circuit according to the invention.

to cause intermittent alarm signals tobe produced indicating the intrusion.

2. Description of the Prior Art Automobile intrusion alarm devices are known in the prior art. However these normally have oneormore disadvantages. For example, one type of device provides a circuit which is actuated to produce audible alarm signals in response to the intrusion, but the signals immediately cease upon closure of the door, hoodor trunk, theopening of which caused actuation of the alarm. Therefore the intruder canmade a quick entry; and remove himself fromthe area before the alarm is heard.

Another type of prior art device causes the automobile horn to be continuously actuated after the car is initially broken into, and therefore cannot bedistin'guished from a 37tuck" horn. Therefore, it may not be noticed as an alarm signal; Still anothertype of prior art device-utilizes a transducer in the .form'of a siren to produce the audible alarm,-rather than the carhorn. However, in some states the use of sirens by private individuals is prohibited, and-furthermore the useof an additional component needlessly increases the costiof the overall alarm device. 3

Stillanother type of-priorart alarm device requires thata manualswitch be actuated in order to turn the'alarm off.

Under certain-conditions theralarm could be actuated for an r extended period of time, and therefore the car battery may be needlessly drained. Further, this type of .device may produce unnecessary and prolonged noise.

Stillother alarm devices function in response to-vibrations or physical contact. Thus,-some prior art circuits have capaci- DETAILEDDESCRIPTION OF THE INVENTION The drawing shows the circuit according to the invention. A

tothe positive supply terminal of battery-C, and its base connected to one end of resistor 4. The other end'of resistor 4 is nected to one end of courtesylamp Band to the movable contact arm of single-pole, single throw switch l. The corresponding stationary contact of switch 1 is connected to ground, along with the other plate of capacitor 3, the negative supply terminal of battery C, one plate of'capacitor, l1, and the'movable contact ann of'single-pole, single throw switch 14. v

The collector of transistor T1 is selectively'cb'iinectable to one end of relay winding'7 through switch 6, the'other end of said relay winding being connected to the other plate of tive inputs whereby if a person approaches the carthe capacitance thereof- Changes to cause actuation'of thealarm. Other devices are responsive to vibration-."However 'su'ch devices'aresubject to.false alarms 'in that a passing truck or personmight accidentallycause, actuationrof the alarm where no intrusion or premeditated tampering is'intended.

' SUMMARY OF THE INVENTION :2

These-and other defects ofprior art alarm devices are solved by the present invention. An electroniecircuitis employed-which provides intermittent actuation-of an audible 1 alarm indicating that the 1 The. circuit is particularly adaptable for use in-conjunction powered by the car batteryJWhen armed, opening of a car door, hood or trunk will cause-intermittent sounding of the car horn. ltthe car door; hood, or trunk which, when opened, initiated actuation of thealarm-is then closed, the car'horn will continue to lie-actuated for a predetermined period of time. The alarm device-will then automatically be deactuated, and will return to thev alert" status.

The electronic circuit employs a transistor-but other equivalent means may also be employed. An RC circuit is employed to bias the transistor to the.,nonconducting' condition until the car is broken into. Then; the RC circuit functions to drive the transistor to conduction and an-interrupter' circuit is employed to cause intermittent actuation of the car horn. Therefore a distinctive audible alarm signal isproduced to provide an indication that the ca has' been broken into. Further, the car battery is not unduly drainedibecause; if the cardoor, hood, or trunk, the opening of which caused actua- I tion of the alarm is closed, .the RC circuitfunctions to maintain actuation of the car horn only for a predetermined period of time. I

Since the circuit utilizes the car horn,'it is notnecesssary to use additional transducer means to produce the audible signal. Thereby the cost ofthe alarm device is minimized.

protected area has been broken into.,,

' nected to' one end of relay tive terminal of battery is, arid to one terminal'of horn 18. The

. other terminal of horn 18 is connected to contact 16, which in capacitor 11. The series connection of relay winding 7 and capacitor 11 is connected through resistor R12 to contact 9. The corresponding stationary contact of switch 14 is. conwinding 15 and to stationary contact l0. Movable contact 8 is connected to ground and is associated with stationary contacts 9 and 10, and 'is selectively controlled by 'energization and deenergization of relay winding 7 to provide the desired connections. Thus when relay winding 7 is suffieiently'energized, contacts 8 and 10 are connected and-when it is deenergized or not sufficiently energized, contacts 8 and 9 are connected.

The other end'ofrelay winding 15 is connected to theposiconjunction with compliment'arycontact l7 is'controlled by relay winding 15 to provide the desiredconnections. Contact 17 isconnected to ground; The positive end'of battery B 'is connected't'o theother-terminal of courtesy lamp 13.

The described circuit functions in the follo'wih'g'manner. In the standby state,-capacitor3 charges'towards the voltage of battery C through the circuit comprising resistor R4, and the base-emitter circuit of transistor T1. The base of transistor T1 is thereby'maintained at apositive potential value that is sufficient relative to the potential at the emitter, to'bias transistor Tl'to the nonconducting state. The circuit is -armed b closing switch 6, although actuating switch 6 to theclosed position does not alter the above-described conditions.

Assume that switch] is now actuated to the'closed'position, corresponding to the opening of a door, hood,trunk, or the I like of the car. A numberof switchesma'y be connected in parallel with switch 1', each corresponding to" different portions of the c'arthat may bebroken into. Then-if any of said 1 portions is disturbed b an intruder,- the alarm will'beactuated.

" When switch] is closed, capacitor 3 dis'dh'arges to ground through diode 2-. The base of transistor T1 is thereby driven sufficiently negative with'res'pect to the emitter to forward bias transistor T1. -'l" his causes a current to flow in the collector circuit which energizes relay winding '7 such as to cause contacts 8 and mm beconnected. This completes the electrical connection to horn relay winding 15 by connecting it to ground, thereby causing said horn relay winding 15 to be energized to connect contacts 16 and 17 together. The connection to horn 18 is therefore completed by connecting it to ground,

thereby causing said horn to be actuated to produce an alarm signal. Switch 14 comprises the conventional horn switch aselectrical connection to horn' relay sociated with the car which, when depressed, completes the winding 15.

During thiscycle of operation; capacitor l l"'charges to a predetermined value and the 'current flowing'injth e collector circuit of-trarisistor Tl decreases, until it'reaches alevel which is'insufficient'to cause relay winding 7t5riiaintaintheconnection of contacts 8 and 10. This connectionthereby dropsout, 

1. An electronic alarm circuit to indicate intrusion into a protected area comprising: an alarm device, control means comprising a transistor and a biasing circuit connected to the alarm device to control operation thereof, actuating means connected to the control means actuated in response to an intrusion into the protected area to cause the control means to complete the electrical circuit of the alarm device and cause actuation thereof, and, interrupter means comprising the series combination of a relay winding and a capacitor interposed between the transistor output circuit of the control means and the alarm device to periodically interrupt actuation of the alarm device tO provide intermittent operation thereof in response to an intrusion into the protected area, the control means having timing means to cause the alarm device to remain actuated for a predetermined period of time after the actuating means are deactuated.
 2. The electronic alarm circuit recited in claim 1 wherein the biasing circuit reverse biases the transistor when the actuating means are deactuated.
 3. The electronic alarm circuit recited in claim 2 wherein the biasing circuit forward biases the transistor when the actuating means are actuated.
 4. The electronic alarm circuit recited in claim 3 wherein the interrupter circuit is connected to the output circuit of the transistor and comprises means to selectively vary the current in said output circuit to cause intermittent operation of the alarm device.
 5. The electronic alarm circuit recited in claim 3 wherein the biasing circuit comprises the series connection of resistance means and capacitance means connected through the control electrodes of the transistor to a source of potential the capacitance means being charged to maintain the transistor in reverse bias condition when the actuating means are deactuated, and the actuating means comprise means to discharge the capacitor when actuated to forward bias the transistor.
 6. The electronic alarm circuit recited in claim 4 wherein the biasing circuit comprises the series connection of resistance means and capacitance means connected through the control electrodes of the transistor to a source of potential, the capacitance means being charged to maintain the transistor in reverse bias condition when the actuating means are deactuated, and the actuating means comprises means to discharge to capacitor when actuated to forward bias the transistor.
 7. The electronic alarm circuit recited in claim 6 wherein the alarm device comprises an automobile horn, the protected area being the associated automobile, and wherein the actuating mean are actuated in response to the opening of an access to the automobile.
 8. An electronic alarm circuit to indicate intrusion into a protected area comprising: an alarm device, control means comprising a transistor and a biasing circuit, said biasing circuit comprising a series connection of resistance means and capacitance means connected through the control electrodes of the transistor to a source of potential, actuating mean connected to said control means comprising means to discharge the capacitance means when actuated to forward bias the transistor in response to an intrusion into the protected area, thereby causing the control means to complete the electrical circuit of the alarm device and cause actuation thereof, and interrupter means interposed between the control means and the alarm device to periodically interrupt actuation of the alarm device to provide intermittent operation thereof in response to an intrusion into the protected area comprising the series connection of a relay winding being responsive to the flow of current of predetermined amplitude therethrough to actuate the alarm device, the control means having timing means to cause the alarm device to remain actuated for a predetermined period of time after the actuating means are deactuated.
 9. The electronic alarm circuit recited in claim 8 wherein the alarm device comprises an automobile horn, the protected area being the associated automobile, and wherein the actuating means are actuated in response to the opening of an access to the automobile.
 10. The electronic alarm circuit recited in claim 8 wherein the actuating means comprises at least one switch connected in parallel with the capacitance means. 